This image has produced some controversy. Some think I may have cheated and stacked daylight cloud images with night time star trails. I will say plainly that I did not do that. Here is the explanation:

Despite the way the shot appears, it is not a double exposure of day and night shots - it is a stack of night shots. You can see all of the shots used in the movie. The "trick" to get this brighter image was to allow Picasa3 to "auto correct" the contrast.

What is really going on, however, is that the moon rose after shooting started and created more and more illumination. The first shots with the clouds (which moved out of the image to the lower left) had very little moonlight on them. You can see where there are ragged parts of the star trails - that's because those portions were obscured by clouds.

The last single frame of the series appeared almost "day like" (only a bit darker than what you see above). The stacking process selected the brightest pixels from each frame.